Elevator brake



Aug 12, am. 1,5M 39 J. W. EROWN ET AL ELEVATOR BRAKE Filed Jan. 24, 1920 Patented Aug. 12, 1924.

UNITED STATES PATENT ()FFICE.

JOHN W. BROWN, OF WEST ALLIS, AND ALEXANDER J. NIGHT, 51%., OF MILVAUKEE, WISCONSIN, ASSIGNORS TO ALLIS-CHALM'ERS MANUFACTURING COIVIPANY, OF MILWAUKEE, WISCONSIN, A CORPORATION OF DEL'AIW'AB-E.

nLnvAron BRAKE.

Application filed'lanuary 24, 1920. Serial No. 354,207.

To all whom it may concern:

Be it known that JOHN W. BROWN and ALEXANDER J. NIGHT, Jr, citizens of the United States, residing at est Allis and 5 Milwaukee, respectively, in the county of Milwaukee and State of Wisconsin, have. invented a certain new and useful Improvement in Elevator Brakes, of which the following is a specification.

This invention relates in general to an improv;d. device for preventing reversal of a rotary haft, and relates more specifically to an im roved brake for stopping an elevator or the like in case the driving power fails.

An object of the invention is to provide a simple and efficient brake for preventing reversal of a rotating shaft or drum.

It has been found desirable in some in 20 stances, to provide hoisting apparatus such as bucket elevators, with a device for positively arresting the motion of the carriers upon failure. of the driving power. If no such braking means are provided, the loaded 25 carriers will quickly reverse their direction of travel upon failure of the driving power, thus causing serious damage and possible destruction of the elevator.

The present invention contemplates the provision of mechanism for positively preventing reverse movement of an elevator or the like. This contemplated result is accomplished by providing a stationary shaft or pivot spaced from and extending parallel to one of the rotating elements of the ele vator, and connecting the rotating elevator element and the pivot by means of a toggle mechanism. I During normal forward oper ation of theelevator this toggle mechanism is flexed. If however, for any reason the elevator tends to reverse its direction of travel. there is a resulting tendency to straighten the toggle mechanism. .This tendency towards straightening of the toggle mechanism exerts braking pressure upon the rotary elevator portions thus preventing reverse movement of the elevator.

A clear conception of an embodiment of the invention and of the mode of operation of a mechanism built in accordance therewith, may be had by referring to the drawing accompanying and forming. a part of this specification in which like reference characters designate the same parts in the various views.

Fig. 1 is a side elevation of an elevator braking mechanism showing the approXi mate relative position of a bucketelevator in dot and dash lines.

Fig. 2 is an end elevation of the elevator brake.

Fig. 3 is a plan view of elevator brake.

Fig. 1 is an enlarged side elevation of a portion of the brake mechanism.

Referring specifically to Figs. 1, 2 and 3, the horizontal shaft 2 represents the upper shaft of a vertically disposed bucket elevator. Secured to the horizontal shaft- 2 is a drum 3 with which coacts an elevator belt l having a series of buckets 5 secured thereto. As illustrated the elevator buckets 5 are normally adapted to travel in an anticlockwise direction as shown by the arrow in Fig. 1, about the axis of the shaft 2 when traveling around the drum 3. Secured to the shaft 2 at one side of the bucket elevator, is a brake-wheel 6 which is rigidly attached to the shaft 2 in any suitable manner. Located laterally of the brake-wheel 6 is a stationary bracket 11 which forms a support for the horizontal pivot the axis of which is parallel to the axis of the rotating shaft 2. The pivot 10 and bracket 11 are connected with the shaft 2 by means of tie-pieces 7 located one, on each side of the brake wheel 6. Displacement of the tiepieces 7 longitudinally of the shaft 2 is prevented by means of the hub of the brakewheel 6 and by means of the collars secured to the shaft A movable toggle link 9 is mounted upon the pivot 10 and has a downwardly projecting rear portion 12 extending along the rear face of the bracket 11. An adjusting cap-screw 13 has screwthrcad coaction with the projection 12 and is engageable with the adjacent surface of the bracket 11 to limit the upward. travel of the link 9 about the pivot 10 as a center. The end of the link 9 nearest the brakewheel 6, carries a pivot 14 upon which a brake-shoe 8 is mounted. The brake-shoe 8 has a facing 16provided with a braking surface'engageable with the peripheral surface of the brake-wheel 6.

The details of construction of the link 9 and brake-shoe 8 are more clearly disclosed in Fig. 4. From the disclosure in this figure it will be noted that the brake-shoe 8 is provided with a detachable facing 16 which cooperates with the brake-Wheel 6 and which may be renewedif necessary. The pivot 1a which connects the brake-shoe 8 with the toggle lever 9 is mounted in an adjustable block 17 which is slidable within the slotted end of the lever 9. An adjusting wedge 19 coacts with the block 17and with an end surface of the slot in the lever 9, the wedge 19 being movable transversely of the lever 9 to vary the position of the block 17 by means of an adjusting bolt 18. The adjusting bolt 18 may be locked in any adjusted position by means of a locking nut 20.

During the normal operation of the ele vator, the brake mechanism is in the position illustrated in Fig. 1 with the connecting pin 14; above a horizontal plane passing through the axes of the shaft 2 and the pivot 10. Rotation of the bucket elevator in its normal or anti-clockwise direction tends to flex the toggle formed by the brake-wheel 6 and brake-shoe 8 as one element and the link 9 as the other element. If for any reason the is reversed, the friction between the peripheral surface of the brake-wheel 6 and the i brakeshoe 8, causes the brake-wheel 6 to carry the brake-shoe 8 in a clockwise direction about the axis of the shaft 2 thereby tending to straighten the toggle connecting the shaft 2 and the pivot 10. This tendency towards straightening of the toggle, causes the brake-shoe 8 to firmly grip the peripheral surface of the brake-wheel 6 and quickly stops reverse travel of the shaft 2 and of the bucket elevator. Vith the brake-wheel6 thus gripped, the tie-pieces 7 positively prevent dislocation of the bracket 11 relatively to the shaft 2.

The rate of operation of the brake may I be varied by adjusting the position of the block 17 and also by limiting the clockwise movement, of the lever 9 about the pivot 10 by adjustment of the cap-screw 13. The various parts of the mechanism are readily removable and are accessible at all times. While the invention has been disclosed as being specifically applied to an elevator of the bucket type, it will be obvious that the principles involved are applicable generally wherever it is desired to prevent reverse rotation of a rotatable shaft.

It should be understood that it is not desired to limit the invention to the exact details of construction herein shown and described, for obvious modificationswithin the scope of the appended claims may occur to persons skilled in the art.

It is claimed and desired to secure by Let ters Patent 1. In combination, a horizontally disposed rotary shaft, a horizontally disposed pivot spaced horizontally from said shaft, and a single toggle connecting said pivot and said shaft, one element of said toggle comprising a link and the other element comprising a brake wheel secured to said shaft and a shoe having surface coaction with said wheel, rotation of said shaft in one direction tending to flex said toggle while maintaining said surface coaction and reverse rotation of said shaft tending to straighten said toggle and stop said shaft.

Quin combination, a rotary shaft, a pivot spaced from said shaft, a tie-men'iber directly connecting said shaft and said pivot, and a toggle located closely adjacent to said tiemember and connecting said pivot and said shaft, one element of said toggle comprising a link and the other element comprising a brake wheel secured to said shaft and a shoe having surface coaction with said wheel, rotation of said shaft in one direction tending to flex said toggle while maintaining said surface coaction and reverse rotation of said shaft tending to straighten said toggle and stop said shaft.

3. In combination, a rotary shaft, a pivot spaced from said shaft, a pair of laterally spaced tie-members directly connecting said shaft and said pivot, and a toggle located between said tie-members and connecting said pivot and said shaft, one element of said toggle comprising a link and the other element comprising a brake wheel secured tov said shaft and a shoe having surface coaction with said wheel, rotation of said shaft in one direction tending to flex said toggle while maintaining said surface coaction and reverse, rotation of said shaft tending tov straighten said toggle and stop said shaft.

In testimony whereof, the signatures of the inventors are afiixed hereto.

JOHN 1V. BROWN. ALEX. J. NIGHT, Jn.

(M meme. 1 at, 

